As turbochargers, there is a turbocharger in which a rotating shaft is supported by a roller bearing. The turbocharger includes a housing having a tubular accommodation portion for accommodating the roller bearing. An outer ring of the roller bearing is fitted into the accommodation portion of the housing, and thus, the roller bearing is supported by the housing. The rotating shaft of the turbocharger is fitted into an inner ring which is rotatable. Accordingly, the rotating shaft can rotate relative to the housing.
In the turbocharger, it is necessary to decrease noise and vibrations during the rotation of the rotating shaft.
PTL 1 discloses a configuration in which an oil film is interposed in a minute gap between an inner peripheral surface of the accommodation portion of the housing and an outer peripheral surface of the outer ring of the roller bearing. According to this configuration, when vibrations are generated by the rotating shaft, damping effects (effects of damping vibrations) can be obtained by a squeeze film damper phenomenon of the oil film.